Hope for Parkinson's patients: 5 studies you may have missed

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(CNN) -- Hope for Parkinson's patients: 5 studies you may have missed

Here's a roundup of five medical studies published this week that can give you new insights into your health, mind and body. Remember, correlation is not causation -- so if a study finds a connection between two things, it doesn't mean that one causes the other.

Hope for people with Parkinson's

Journal: Cell Reports

Scientists at Harvard University say they see promising signs from their study on an experimental treatment for Parkinson's disease. The researchers transplanted tissue from fetal dopamine cells into the brains of patients with Parkinson's in Canada.

Patients with severe symptoms experienced 50% fewer symptoms in the years after surgery. People who had been taking medication to control their Parkinson's but found that the medicine no longer worked also saw significant improvements after surgery.

Looking at the brains of five patients after they died from non-Parkinson's related illnesses, the scientists found that the transplanted cells stayed healthy. Earlier research led scientists to hypothesize that the cells would become corrupted, but the cells remained functional for at least 14 years after the patients got them. This is the first proof that this kind of transplant method could work.

"Though it is encouraging and even exciting to see some PD cells survive over a decade following a human transplant, we are still humbled by the challenges in developing a viable therapy," Dr. Michael Okun, national medical director for the National Parkinson Foundation, cautioned. "All transplants for Parkinson's disease remain hampered by an inability to constitute a complex multilevel brain circuitry."

Next, researchers will see whether they can replicate the success of this procedure using stem cells instead of the more controversial fetal cells.

To lose weight, stop counting calories

Journal: JAMA

The key to losing weight is not about "dietary bookkeeping" - meaning you can't merely eat less and exercise more. "Most people will lose that battle," write Dr. David Ludwig and Mark Friedman in the latest edition of JAMA.

The two world-renowned obesity experts say that effective weight loss should be more about what you eat. That is because different food interacts differently with your body.

A real diet should not focus solely on how much fat or how many calories are in that food, the experts say. For instance, nuts are good for you despite their high calorie and fat content. But an ice cream sandwich is not. It may be low in calories, but it also has a significant number of refined carbohydrates, which will cause your insulin level to spike.

Because of the way insulin impacts you at your cellular level, fat cells will absorb the calories. But there aren't enough nutrients in that ice cream sandwich to give your body the energy it needs, so your body craves more food, thinking it is still hungry.

The munchies and sleepless nights: Marijuana may hurt your sleep

Journal: Sleep

Often people will say they smoke pot to relax, but a new study found that most marijuana users have trouble getting a good night's sleep.

The study comes from researchers at the University of Pennsylvania who looked at the drug history of 1,811 participants who responded to the 2007-2008 National Health and Nutrition Examination Survey. The adults were from 20 to 58.

All marijuana users reported increased problems with sleeping through the night, feeling sleepy during the day and had trouble falling asleep.

Marijuana users who started using before age 15 had the most trouble. They were twice as likely to be sleep deprived as the others.

Heart-stopping pollution: What bad air might do to you

Journal: Heart

Pollution can create more than a bad asthma day for people who live in smoggy areas.

In a new study, scientists looked at data that tracked hospital admissions in Wales and England from 2003 to 2009. They combined data on people who had heart attacks or strokes, and death data, with data collected on pollution.

The good news is there is no evidence that short-term exposure to air pollution increases your risk for a heart attack or stroke. Nor was there a clear link between pollution and cardiac deaths with one exception: Deaths because of irregular heartbeats and blood clots in the lungs did go up with high pollution.

Scientists also found more people were admitted to the hospital on days there were high levels of nitrogen in the air.

E-cigarettes send an increased number of callers to poison hotlines

Journal: JAMA

Poison centers are getting busier as more people use e-cigarettes.

Public health investigators compared data from poison centers around the country from September 2010 and February 2014. What they found was more calls about e-cigarette exposure;

these e-cigarette-related problems made up about 41% of the calls.

The majority of the calls about regular cigarettes involved kids younger than 5. The e-cigarette calls were split between children and adults.

Most callers had questions about exposure to the e-cigarette from inhaling it or having the chemical come into contact with a person's eyes or skin. About 58% of the callers had a bad reaction, compared with 36% of those exposed to regular cigarettes.

People who didn't feel well after exposure to electronic cigarettes reported problems with eye irritation, vomiting and nausea.